Fibre container construction



p 21, 1955 T. E. DOBBINS ET AL 3,

FIBRE CONTAINER CONSTRUCTION Filed Sept. 11, 1965 2 Sheets-Sheet 1 IJNVENIWRS paemr (ls M155 Maw f2 4 6501961. 05042 say/Puma? BY Mam Sept.21, 1965 T. E. DOBBINS ETAL FIBRE CONTAINER CONSTRUCTION 2 Sheets-Sheet2 Filed Sept. 11, 1963 IIIIIIIIIII IIIIIIII-III iii o 0 88 0 o9o8o o o0928 o o 9020 o 62%?62 030m say/90mm BY M a. m

A 7 TOE/V5 Y United States Patent 3,207,410 FIBRE CONTAINER CONSTRUCTIONThomas Edward Dobbins, Elmhurst, Il'l., Delbert Charles Foord, GardenCity, N.Y., and George Oscar Schroeder, Palatine, Ill., assignors toAmerican Can Company, New

York, N.Y., a corporation of New Jersey FiledSept. 11, 1963, Ser. No.308,250 18 Claims. (Cl. 229-3.1)

This is a continuation-in-part of application Serial No. 241,823 filedDecember 3, .1962 in the names of T. E. Dobbins and D. C. Foord forFibre Container, now abandoned.

This invention relates to the manufacture of liquidtight containers andmore particularly it relates to a container construction having improvedliquid barrier and strength characteristics.

Because of their relatively low cost, liquidproof fibre containers havebecome quite popular for marketing such products as milk, fruit juices,non carbonated beverages, and similar liquids. The structuralrequirements for containers of this type are rather rigid in that theymust be liquid-tight to prevent leakage, durable to Withstand a greatdeal of handling between the time of manufacture and actual use, and,Where the product contained therein is a comestible for humanconsumption, they must also maintain the product in a sterile anduncontaminated condition.

While these requirements have been fairly well maintained by the wellknown waxed fibre or paperboard type of container, containermanufacturers continue to seek ways of improving container strength,particularly abuse resistance, of reducing the amount of wax utilized incoating the containers and thereby reducing the unit cost of suchcontainers, and of providing a container construction having greaterattractiveness and market appeal. It has been found that the amount ofwax utilized in coating the containers can be materially reduced bylaminating or coating the fibre container stock with a wax-proof coatinglayer which prevents the wax from penetrating or impregnating the fibrestock.

One satisfactory lamination technique which prevents the aforesaid waxpenetration of the container fibre stock and also prevents liquid orvapor moisture from saturating and weakening the fibre involves coatingboth the inner and outer container fibre stock surfaces with a film ofmoisture-impervious plastic, such as polyethylene and then wax flushingthe interior of the container to further protect against seam leakage.This lamination technique not only prevents both wax and moisturesaturation of the fibre container stock but also provides a containerhaving no exterior wax coating and thus offering an attractive packagehaving a high degree of market appeal.

Another satisfactory lamination technique which prevents wax penetrationof the container fibre stock involves use of a mineral hold-out coatingon the exterior container surfaces and a polyethylene film on theinterior container surfaces. The hold-out coating prevents waxsaturation but does not protect against moisture penetration andsaturation. However, When the entire container is wax dipped, the outerwax coating prevents moisture penetration and the inner wax coatingprotects against seam leakage. This lamination technique protectsagainst moisture and wax saturation of the container fibre stock andalso provides a container wherein the unit cost can be reduced byelimination of the outer polyethylene coating.

While lamination of fibre stock by either of the aforementionedtechniques produces a container material having the desirable propertiesof preventing wax and/or moisture penetration and saturation, containersmade 3,207,410 Patented Sept. 21, 1965 from these materials stillencounter certain difficulties, foremost among these being end weaknessand seam leakage. When the container material is fabricated into atubular body and end closures are applied to form a liquid-tightcontainer, the body portions at the corners and adjacent the end seamsare naturally subjected to severe working stresses during assembly.Often such working will cause the plastic films or the hold-out coatingon the fibre wall to fracture or crack and, in such instances, evensubsequent wax coatings are not completely satisfactory to preventweakness and leakage at these areas, since the film or coating is stillimperforate enough to prevent suflicient wax penetration of the fibrewith its accompanying strengthening effects.

The problem becomes even more acute during handling and shipping of suchcontainers. Since the containers are filled with liquid contents andsubsequently handled and shipped, the liquid contents act as a hydraulichead causing severe jouncing and abuse of the lower body and end seamareas in particular. Often this abuse is severe enough to flake oif theinner Wax coating and to fracture the inner fibre plastic coating thusallowing the liquid contents to seep into the fibre and cause leakagewhich causes the container to weaken or sag or to flake off the outerwax coating and fracture the outer plastic film or hold-out coating thusallowing ambient moisture to seep into the fibre.

It thus becomes apparent that, while it is possible to manufacturecontainers having coatings suitable for preventing wax impregnation ofthe fibre stock and thus having the benefits of decreased unit cost andmore attractive appearance due to the elimination of the mottled effectoften caused by wax impregnation, such benefits are achieved onlythrough the sacrifice of the beneficial strengthening effects of waximpregnation and accordingly, such containers are more prone to leakageat the worked areas and the weakness and sagging concomitant with suchleakage.

It is therefore an object of this invention to provide a liquidproofcontainer of laminated stock having an improved construction in theworked areas of the container particularly the body.

Another object of this invention is to provide a liquidtight laminatedcontainer having end areas of improved strength and resistance to abuseand softening.

A further object of this invention is to provide a laminated containerwhich prevents wax impregnation of the container stock in all butselected areas.

Still another object of this invention is to provide a liquid-tightmoistureproof laminated fibre container having a wax impregnated endseam and necked-in construction.

Yet a further object of this invention is to provide a leakproof fibrecontainer having a selectively interrupted inner and/ or outer coatinglayer which permits selective wax impregnation of the fibre.

Numerous other objects and advantages of the invention will be apparentas it is better understood from the following description, which, takenin connection with the accompanying drawings, discloses a preferredembodiment thereof.

The foregoing objects are attained by manufacturing a container from alaminated blank comprising a paper or fibre-board backing layer and awax impermeable inner and outer layer, at least one of which isselectively interrupted or terminated at those portions or areas of theblank which are worked in the formation of the con tainer such as thescore lines at which the corners are formed and the necked-in portionsof the container. Thus, when the container is assembled and given a waxcoating, the Wax penetrates or impregnates the fibre backing layer atthose areas where the wax impermeable layer is interrupted orterminated, thereby strengthening those vulnerable corner, necked-in andend seam areas and protecting them against weakening from liquid seepageinto the fibre. The term discontinuous or discontinuity as used hereinis considered to be generic to the concept of interrupting, terminatingor otherwise degrading the wax impermeable coating.

Referring to the drawings:

FIG. 1 is a perspective view of a container constructed in accordancewith the present invention;

FIG. 2 is a plan view of one form of body blank used in construction ofthe container illustrated in FIG. 1;

FIG. 3 is a fragmentary enlarged sectional view taken substantiallyalong line 33 of FIG. 1 and illustrating one embodiment of the presentinvention;

FIG. 4 is a greatly enlarged fragmentary sectional view illustrating indetail the bottom end seam construction of FIG. 3;

FIG. 5 is a greatly enlarged fragmentary sectional view, similar to FIG.4, and illustrating a modification of the embodiment of FIGS. 3 and 4;

FIG. 6 is a greatly enlarged fragmentary view of the bottom end seam ofa modified form of container and illustrating how the embodiment of theinvention illustrated in FIGS. 3-5 can be applied to different forms ofcontainers; and

FIG. 7 is a greatly enlarged fragmentary sectional view of the bottomend seam of a container similar to that shown in FIG. 1 and illustratingan alternate embodiment of the present invention.

The configuration of the container illustrated in FIG. 1 is a well knowntype being of the general character of the container disclosed in US.Patent No. 2,085,979 issued to John M. Hothersall. Briefly described,this container, generally designated 20, comprises an elongated tubularbody, generally designated 22, preferably of square or rectangularcross-section, top and bottom end closures 24 and 26 respectivelysecured to the tubular body, and a hinged plug closure element 28closing a pouring opening in the top end 24. The body 22 is formed froma single blank which is folded with its opposite ends overlapping toform a side seam 30. The top and bottom margins of the body arenecked-in as generally designated at 32 and 34 respectively and are thenfolded over the edges of the end closures 24 and 26 to form reinforcedend seams 36, 36.

FIG. 2 illustrates a body blank generally designated 38 and constructedin accordance with one embodiment of the present invention. The blank 38comprises a main layer 40 of ordinary fibre or paperboard stock,approximately 0.012 to 0.022 inch thick, and a thin film 42 ofthermoplastic resin material, preferably polyethylene having a thicknessof approximately 0.0005 to 0.003 inch, coated to that surface of themain layer 40 which will be on the interior of the finally formedcontainer. Appropriately spaced parallel fold lines 44 are formed in theblank to define therebetween, those portions of the blank 38 which willdefine the side walls of the body 22 when the container is erected. Theblank 38 may be made in any desired manner, but the preferred practiceis by the well known technique of extrusion coating a continuous fibreweb which is then cut into individual body size blanks. In mostinstances it is desirable to have an exterior moisture-imperviouscoating for the container and one such coating can be a thinpolyethylene film 45, similar to the film 42, but laminated to theopposite surface of the main fibre layer 40 and thus forming an exteriorcoating when the container is erected.

When a blank such as 38 is erected into a container and assembled withthe end closures, the resultant container will have a cross-sectionalconfiguration as shown in FIG. 3 and in greater detail in FIG. 4.

Remembering that the basic concept of the present invention is toprovide for selective wax impregnation of the fibre, e.g. waximpregnation of the fibre layer in the necked-in areas 32 and 34 and inthe end seam areas 36, 36, it is thus essential that the wax impermeablelayer be terminated or interrupted at those areas of the container. Inthe embodiment illustrated in FIGS. 2-6, the wax impermeable layer isthe thermoplastic film 42 which is laminated to the blank 38 on thesurface which is to form the interior of the container. In thisparticular embodiment of the invention, the modification illustratingthe wax impermeable layer terminated at the end areas is shown in FIGS.2-4 and the modification illustrating the wax impermeable layerinterrupted at the end areas in shown in FIG. 5.

Referring now to the modification of FIGS. 2-4, it can be seen that thewax impermeable layer or thermoplastic film 42 terminates short of thetop and bottom ends of the blank. Strips 46, 46 of adhesive, preferablyof the hot tack variety, are applied at the extreme top and bottom edgesof the blank which correspond to the folded-over portions of the endseams to provide the means of securing the end closures 24 and 26 to thebody 22. Between the terminal ends of the thermoplastic film 42 and theadhesive strips 46, film-free margins 48, 48 are formed. These margins48, 48 define regions of exposed fibre from the main layer 40 and whenthe container is assembled, these margins form the interior surfaces ofthe necked-in portions 32 and 34.

When the container is assembled, the interior thereof is flushed orotherwise coated to receive a thin wax coating 50, as shown in FIGS. 3and 4. Since most of the interior of the container is covered by the waximpervious layer 4 2, the wax coating 50 cannot penetrate into thefibre; however, in the film-free areas 48, 48 at the neckedin portions32 and 34 adjacent the end seams 36, 36, the wax can freely penetrate orsaturate the fibre layer 40. This wax impregnation of the fibre in thevulnerable necked-in and end sea-m areas is suflicient to strengthen andrigidify the heavily-worked fibre in these areas and thereby overcomethe problems of sag and low abuse resistance which otherwise occur ifthe fibre remains dry. As can be seen in FIG. 4, the wax whichimpregnates the fibre is transferred by capillary action, completelythroughout the necked-in portions, into the folded-over end seam areas,and even to a point slightly above the terminal edge of the waximpervious layer 42, thereby assuring strengthened end seam andnecked-in areas.

The wax coating 50 need not be very 'heavy, thus lowering unit cost [interms of quantity of wax used and flushing time, and the wax itself canbe paraifin or microcrystalline or amorphous wax, or a mixture of thetwo, which is compatible with the plastic film 42. As the Wax is appliedas a coating 50, it builds up in a small fillet at the bottom end due tothe tendency to drain down before solidifying, and it thus penetrateswell into those portions of the body 22 and bottom end 26 which areconcealed in the seam 36, thus providing a liquidproof end seam ofimproved strength.

As seen in FIG. 3, the top end construction differs slightly from thebottom end construction to the extent that the upper necked-in portion32 is not deformed into full engaging contact with the inner marginaledges of the top closure 24 While the lower necked-in portion 34contacts the inner marginal edges of the bottom closure 26. Furthermore,the top end closure 24 is ordinarily coated on both the interior andexterior surfaces with protective films 5 2 and 54, respectively,whereas the bottom end closure 26 is ordinarily of heavier stock and iscoated on its exterior surface only with a protective film 56, theinterior wax coating 50 providing the protective barrier on its interiorsurface, The upper film-free area 48 not only provides for the desiredimpregnation of the necked-in portion, as at the bottom end, but alsoenables the wax coating 50 to migrate fully between the nonengagingsurfaces of the neck-in 32 and the top end closure 24 and extend fullyinto the top end seam 36 thereby saturating the peripheral edge of thetop closure 24.

This provides a container having strengthened necked-in portions andliquidproof end seams at both ends of the container. However, as wasaforementioned, the bottom neck-in and end seam receive the greatestabuse during handling and shipping since the liquid container contentsact as a hydraulic head which is constantly jiggling and j-ouncing andapplying pressure to the lower end areas. Thus, in some instances, itmay be desirable to restrict the use of the present invention only tothe bottom end of the container.

In the modification shown in FIG. 5, the container construction issimilar to that previously described except that the wax impervious film42 is not terminated at the necked-in areas. Instead, the film isdeliberately interrupted or disrupted by knurling, jouncing or othersimilar operation to form marginal bands of perforations 58 extendingover the necked-in portions and the folded-over end seam portions. Theperforations 58 may :be pinholes, slits or other types of puncturesrandomly spaced along the transverse margins of the body blank where thefilm-firee areas 48, 48 were located in the modification of FIG. 2. Theperforations 58 should be of sufficient size to permit ready migrationof the wax fro-m the interior wax coating 50 through the plastic film 42and into the fibre layer 40 to enhance the fibre with the beneficialproperties previously described. In forming the perforations 58, acertain amount of disruption of the underlying fibre will occur but thisshould be kept to a minimum, preferably no greater than 0.002 inchpenetration, to avoid impairing :the strength of the fibre layer 40.While it is possible to terminate the plastic film 42 short of the edgesof the blank and to utilize separate strips of adhesive such as 46, 46of FIG. 2, it is preferable in this modification to extend the plasticfilm -42 completely to the edge of the blank and to leave the extremeouter edges of the film undisrupted by the perforations '58. In thisway, an unperforated band of plastic film is provided at the extremeedges to act as the adhesive for securing the end closures to thecontainer.

While it is preferred that the embodiment previously described beemployed with containers having a neckedin portion, such as those shownin FIGS. 1 and 3, it is by no means limited to such a construction andto illustrate this, FIG. 6 shows the embodiment applied to a differentform of container wherein a container body 60 is formed from a laminatedblank having a main fibre layer 62 to which is laminated an interior waximpermeable thermoplastic film 64 and, if desired, an exteriormoisture-impervious thermoplastic film 66. The body 60 is turned atright angles into an inwardly extending flange 68, and a cupwshaped endclosure 70 having an upstanding fiange 72 is fitted over the body intelescoped relation. The inner wax impermeable film 64 is terminatedshort of the inturned fiange 68 or is interrupted in the region thereofto leave an area of exposed fibre 66. Thus, when the finally formedcontainer is interiorly fiushed to receive a wax coating 74, the waximpregnates this area of exposed fibre, as shown, and provides an endseam construction of improved abuse and softening resistance.

An alternate embodiment of the invention is shown in FIG. 7 wherein acontainer body 22a, similar to container body 22, is necked-in at 34aand then folded-over to secure an end closure 26a by means of an endseam 36a. The container body is comprised of a main fibre or paperboardlayer 40a, an inner wax impermeable thermoplastic fil-m 42a, and anouter wax impermeable layer or hold-out coating '76, shown greatlyexaggerated in thickness for purposes of illustration. The inner film42a is similar to the film 42, preferably polyethylene, and is generallyapplied by extrusion coating. Its marginal end portions can serve as theadhesive for securing the end closures, as was described in connectionwith film 42 in FIG. 5. The outer hold-out coating 76 is a mineralcoating which can vary extensively in composition provided it has twospecific properties; namely, it must be wax impermeable to the pointthat wax cannot penetrate through it and it must be frangible in that itmust be inflexible enough to fracture when scored, as will be presentlydescribed. One suitable coating composition is comprised mainly of claypigment with a protein binder, although the binder can also be apolyacrylic or polyvinyl acetate emulsion. Starch 'al-ginate orstarch-carboxy methyl cellulose coatings are also acceptable. Thesecoatings can be applied by trailing blade techniques or other suitablecoating procedures.

The hold-out coating 76 can be scored, scuffed, jounced or otherwisefractured or mechanically degraded in the necked-in areas to createfractures through which a subsequently applied wax coating can penetratethe fibre. As an illustration, a pair of scored grooves 78 and shown inFIG. 7 extending through the hold-out coating 76 and into the underlyingfibre a. These scored grooves completely encircle the container in thenecked-in area 34a and, if desired, in the necked-in area 32a, notshown. As was the case with the perforations 58 of FIG. 5, it isdesirable that the scored grooves 78 do not extend deeply into the fibrelayer 40a lest they weaken it.

Since the hold-out coating 76 is wax impermeable but not liquidimpervious, and since wax penetration is desired through the fracturedareas of the hold-out coating, it is necessary to apply an outer waxcoating b as well as an inner wax coating 50a and this is generallyaccomplished by wax dipping the entire assembled container. When this isdone, the wax from the outer coating 50b passes through the waximpermeable coating 76 and into the fibre 40a by means of the scoredgrooves 78. Capillary action distributes the wax throughout the fibre inthe necked-in portion 34a thereby strengthening it and preventing sag orweakening. Additionally, the outer wax coating 50b covers the end of thebody 22a, saturating the peripheral edge thereof, and also costs the endclosure protective film 56a, thus providing a wax barrier at the edge ofthe interface between the body inner film 42a and the end closure film56 to thereby prevent leakage at the end seam 36a. As shown in FIG. 7,the inner wax impermeable layer 42a is not interrupted, so all the waximpregnation occurs by the wax from the outer coating 50b penetratinginto the fibre. However, it is Within the scope of this invention todegrade or discontinue both the inner coating 42a, such as is shown inFIGS. 2-5, and the outer coating 76, such as is shown in FIG. 7, tothereby achieve wax penetration by both the inner and outer wax coatings50a and 50b. But in actual practice this has not proved to be necessarysince satisfactory results have been achieved by wax penetration fromone side only and the results have been somewhat the same whetherthe-penetration is from the inside out, as shown in FIGS. 3-5, or fromthe outside in, as shown in FIG. 7.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description and it will beapparent that various changes may be made in the form, construction andarrangement of parts without departing from the spirit and scope of theinvention or sacrificing all of its material advantages, the formhereinbefore described being merely a preferred embodiment thereof.

We claim:

1. A leakproof container for liquid products comprising:

a tubular laminated container body;

a top end closure; and

a bottom end closure;

said top and bottom end closures being secured to said container body byliquid-tight end joints at opposite ends of said container body;

said laminated container body including a main layer of fibre, a waximpermeable coating adhered to said fibre layer, and a wax coatingsuperimposed upon said wax impermeable coating;

said wax impermeable coating being discontinuous adjacent at least oneof said end joints to expose said fibre layer to said wax coating topermit wax from said coating to impregnate and rigidify said fibrelayer.

2. A leakproof container as defined in claim 1 wherein said waximpermeable layer is a thermoplastic film.

3. A leakproof container as defined in claim 2 wherein saidthermoplastic film is rendered discontinuous adjacent said end joint byterminating a predetermined distance therefrom.

4. A leakproof container as defined in claim 2 wherein saidthermoplastic film is rendered discontinuous adjacent said end joint byperforations formed within said film.

5. A leakproof container as defined in claim 1 wherein said waximpermeable layer is a frangible mineral holdout coating.

6. A leakproof container as defined in claim 5 wherein said hold-outcoating is rendered discontinuous adjacent said end joint by selectivefracturing thereof.

7. A leakproof container of improved construction comprising:

a tubular laminated container body; and

top and bottom end closure secured to opposite ends of said containerbody in interfolded end seams;

said laminated container body including a fibre layer,

a wax impermeablelayer superimposed on one surface of said fibre layer,and a wax coating superimposed on said wax impermeable layer;

said Wax impermeable coating being discontinuous adjacent at least oneof said interfolded end seams to permit wax from said wax coating toenter the folds of said end seam to strengthen the seam and render itleakproof.

8. A leakproof container as defined in claim 7 wherein a moistureimpervious layer is adhered to the other surface of said fibre layer.

9. A leakproof container as defined in claim 8 wherein the waximpermeable layer is a mineral hold-out coating and the moistureimpervious layer is athin thermoplastic film.

10. A leakproof container as defined in claim 8 wherein both the waximpermeable layer and the moisture impervious layer are both thinthermoplastic films.

11. A laminated fibre container of improved construction comprising:

a tubular container body of laminated construction and having an upperand lower end;

said container body having necked-in portions adjacent its upper andlower ends;

a top end closure; and

a bottom end closure;

said top and bottom end closures being secured respectively to the upperand lower ends of said container body by interfolded end seams;

said interfolded end seams being formed between said container body andsaid end closures immediately adjacent said necked-in portions;

said container body laminated construction including a main fibre layer,a wax impermeable coating adhered to said fibre layer, and a wax coatingsuperimposed on said wax impermeable coating;

said wax impermeable coating being discontinuous at said necked-inportions to expose the fibre layer therebeneath to said wax coating topermit the wax from said coating to penetrate into said fibre thusstrengthening and rigidifying said necked-in portions and strengtheningand sealing said interfolded end seams to prevent leakage.

12. A laminated fibre container as defined in claim 11 wherein said waximpermeable layer is a thermoplastic film.

13. A laminated fibre container as defined in claim 12 wherein saidthermoplastic film is rendered discontinuous at said necked-in portionsby terminating a predetermined distance therefrom.

14. A laminated fibre container as defined in claim 12, wherein saidthermoplastic film is rendered discontinuous at said necked-in portionsby perforations formed within said film.

15. A laminated fibre container as defined in claim 11 wherein said waximpermeable coating is adhered to said fibre layer on the surfaceforming the interior of said container.

16. A laminated fibre container as defined in claim 11 wherein said waximpermeable coating is a frangible holdout coating.

17. A laminated fibre container as defined in claim 16 wherein saidhold-out coating is rendered discontinuous at said necked-in portions byselectively fractured areas formed within said hold-out coating.

18. A laminated fibre container as defined in claim 17 wherein saidhold-out coating is adhered to said fibre layer on the surface formingthe exterior of said container.

References Cited by the Examiner UNITED STATES PATENTS 2,004,041 6/ 35Driver. 2,555,315 6/51 Carroll.

3,070,277 12/62 Moore 229-37 3,108,730 10/ 63 Reinsberg 229-7 FOREIGNPATENTS 225,010 10/59 Australia.

FRANKLIN T. GARRETT, Primary Examiner.

1. A LEAKPROOF CONTAINER FOR LIQUID PRODUCTS COMPRISING: A TUBULARLAMINATED CONTAINER BODY; A TOP END CLOSURE; AND A BOTTOM END CLOSURE;SAID TOP AND BOTTOM END CLOSURES BEING SECURED TO SAID CONTAINER BODY BYLIQUID-TIGHT END JOINTS AT OPPOSITE ENDS OF SAID CONTAINER BODY; SAIDLAMINATED CONTAINER BODY INCLUDING A MAIN LAYER OF FIBERS, A WAXIMPERMEABLE COATING ADHERED TO SAID FIBRE LAYER, AND A WAX COATINGSUPERIMPOSED UPON SAID WAX IMPERMEABLE COATING; SAID WAX IMPERMEABLECOATING BEING DISCONTINUOUS ADJACENT AT LEAST ONE OF SAID END JOINTS TOEXPOSE SAID FIBRE LAYER TO SAID WAX COATING TO PERMIT WAX FROM SAIDCOATING TO IMPREGNATE AND RIGIDIFY SAID FIBRE LAYER.